Frequently Asked Questions About EMI and RFI

There is a lot to know when it comes to EMI and RFI shielding. We have compiled a list of a few frequently asked questions and answers about electromagnetic interference. We hope that these answers help your understanding of the field.

What is conducted electromagnetic interference?

Conducted EMI is the result of direct contact of the conductors. When electrometric problems occur in the conductor they usually radiate out. EMI shield can help mitigate this. This interference is usually cause by one of a few things.

  • Changing power supplies
  • Certain AC monitors are prone
  • A Microcompressor

The conductor is not distributing energy evenly, and as such there are multiple problems that may begin to occur.

  • Proximity Effect: this problem is exclusive to conductors that carry only alternating currents. When two wires are close, and one's magnetic field is creating a longitudinal eddy in the other, this is the proximity effect. It will cause resistance to increase, which means that undesirable heat will be created.
  • Skin Effect:  This is also another problem for alternating eclectic currents (AC). This disturbance causes most of the electrical current to be pushed out towards the skin of the conductor. In areas where the skin depth is less, the resistance of the conductor will increase. Eddy currents also cause this problem. When these currents have a changing magnetic field, which is the result of alternating currents, the problem begins.

What is radiated interference?

This interference, unlike conducted interference, is the result of induction. This is of course only when there is no physical contact of the conductors. One cause of this problem is a result of an electrical power cord. It could be malfunctioning (this has nothing to do with the changing of cords). This is because some cords act like antennas. Changing the cord for one that doesn't have antenna like properties, or getting shielding, could help fix the problem.

What is the International Electrotechnical Commission?

The IEC (International Electrotechnical Commission) is reasonable for setting the worldwide standards for both radiated and conducted electromagnetic interference. This allows people to accurately measure the level of interference they are dealing with. These standards apply for domestic and commercial uses. There are also special standards. Besides the IEC, there are local standards in Europe, such as the EN (European Norms) and the European Committee for Electrotechnical Standardization.

Related Reading

  • Understanding RFI

    Grasping the concept of RFI can be a difficult task. The first productive step to take is to understand what the acronym RFI means.